Title: Heat flow estimation and quantification of geothermal reservoir of a basement terrain using geophysical and numerical techniques

Abstract

The occurrence and manifestation of warm and hot springs gives a hint to the availability and abundance of geothermal resources in Nigeria. So for the first time we estimated and quantify the geothermal energy resource potentials in Ikogosi Warm Spring area (IKGWS) and environs using geophysical and Numerical methods. The results from heat flow computation from aeromagnetic investigations and volumetric estimation confirmed there are zones in the IKGWS with anomalous heat flow and great prospects of geothermal energy for direct and indirect applications. The heat flow estimated for the IKGWS and environs ranged from 75 to 127 mW/m2 with an average value of 100 mW/ m2 while temperature gradient varied from 28 to 48 °C/Km with a mean value of 38 °C/Km. Also the Curie point depth (CPD) estimated ranged from 12 to 21 km with a mean value of 16 km. The power output of 2 MWe can be produced with 90% confidence and production greater than or equal to 3.7 MW with 5% confidence. The IKGWS isolated will produce 0.9 MWe if the recoverable heat is used for 25 years. The outcomes implied that IKGWS can primarily sustain a 0.9 MW power plant for a period of 25 years and likely extension will be subjected to further well-defined drilling and site data performance availability. The simulation results show that an estimated stored heat in-place of 0.65–1.95 × 1018 J can be expected from the inferred resource areas at 90% probability. This figure is equivalent to electric power generation potential of 3.2–9.6 MWe or annual electricity generation of 25–76 GWh at the same probability rate. Therefore Nigeria may appear on the global geothermal map by generating power and direct utilization of geothermal energy in IKGWS.